Desk top publishing (local printing by means of specialized software and a personal computer) has become widespread to the point that personal computers readily permit the user to effect high grade printing and publishing with various controllable fonts and point sizes as well as with the ability to print bit-mapped graphics, either locally generated or from pre-packaged clip art. Printers of choice for such desk top publishing are of the Laserjet.RTM. (trademark of Hewlett Packard) or laser printer variety having copier engines and which operate with dry toner and developers. These printers operate at relatively high speed (currently on the order of from about 8-16 ppm) with high quality output (600 dpi and higher) and are capable of providing printing and graphics, limited only by available software.
A second, less popular (except in portable applications), slower (1-2 ppm), lower scale and less expensive printer type is that of the Deskjet.RTM. (trademark of Hewlett Packard) or inkjet variety, which, as the name implies, operates with the dispensing of an ink jet on paper or labels to effect the printing. These printers are similarly capable of providing printing and graphics (though usually with ink densities only in the 300 dpi range for inexpensive portable units), limited by available software. The most common of such printers use the bubble jet technology, wherein ink bubbles are controllably sprayed on the paper in the form of closely spaced dots (which dry upon contact with the paper), to form letter and number characters (text) and graphic art and designs. Specialized versions of these printers have multiple ink dispensing cartridges, which provide a multi-color printing capability in a low cost printer.
The aforementioned printers are not however capable of anything other than normal flat printing. Accordingly, higher scale stationery, such as business cards and letterhead paper, requiring raised lettering, are prepared by professional engravers or thermographers for printing the raised lettering. In the process used by the latter, text or graphic material to be raised is initially completed and then used to create a printing plate or duplicating sheets (similar to a stencil), image created xerographic type templates or similar print application means. The printing plate or similar print application means is then used in a printing press or the like to apply thermographic ink to a paper base. The inked paper is then subjected to a dusting with a thermographic powder, formulated to adhere only to the inked portion of the paper, with excess powder being removed from the paper and recycled. Thermographic activation heating to about 270.degree.-300.degree. F. is then used to cause the adhered powder and ink to rise, to form the raised text or graphics. With the current state of thermography it is not possible to print with alternate sites of raised and non raised lettering and/or graphics in a single pass. Instead two passes are required, one for the flat printing and one for the raised printing, with attendant problems of alignment and proper registration.
A second type of printing requiring raised characters is that of braille printing, i.e., representation of alphabet letters by raised dots (up to six dots/character) in varying configurations. These dots or characters, which are read by finger touch, must be of a minimal standard height (recommended height being 0.019 inches) for touch sensitive reading by the blind. Currently, the various means for braille printing are either very labor intensive, or require expensive machinery and processing. Thus, braille printing has been effected by using a braille typewriter which impresses dots on a heavy stock paper or cardboard, such that the dots are raised on the other side of the stock. Alternatively, pre-fabricated braille lettering is painstakingly adhered to a substrate. Recently, machines using a duplicating engine to provide substitutes for the printing plate, have been developed for printing of braille and other raised lettering and graphics in a thermographic process. These machines, however embody sophisticated technology, are very expensive, and are accordingly not amenable for use in common desk top publishing applications. Even with the sophistication of the machines, simultaneous printing of raised and non-raised portions is still not possible, such as the printing of regular text with corresponding clear raised braille print thereon.
It is therefore an object of the present invention to provide a low cost system for producing raised lettering and graphics in desk top publishing applications.
It is a further object of the present invention to produce such raised lettering and graphics by means of a personal computer and an inkjet type printer.
It is yet another object of the present invention to provide a means for the economical printing of braille lettering on regular paper and label stock.
It is a still further object of the present invention to provide a means for simultaneous printing text and graphics with predetermined raised and non-raised portions and/or with multiple colors.
These and other objects, features and advantages of the present invention will become more evident from the following discussion and drawings in which: